1. Field of the Invention
Exemplary embodiments of the present disclosure relate to an imaging-material container from which imaging material is supplied to an image forming unit, and more specifically to an imaging-material container capable of reducing the residual amount of imaging material remaining therein after use, an ink cartridge including the imaging-material container, and an image forming apparatus including the ink cartridge.
2. Description of the Background
Image forming apparatuses are used as printers, facsimile machines, copiers, multi-functional peripherals having two or more of the foregoing capabilities, or plotters. As one type of image forming apparatus employing a liquid-ejection recording method, an inkjet recording apparatus is known that uses a recording head for ejecting droplets of ink.
For example, in an on-demand-type inkjet recording technique, a diaphragm is provided at a portion of a wall of a chamber containing ink and deformed by, e.g., a piezoelectric actuator to change the internal volume of the chamber to increase the pressure for ejecting ink. In one technique, a heater for generating heat by application of electricity is provided in the chamber. Heating of the heater generates bubbles to increase the pressure in the chamber, thereby ejecting ink.
With recent increases in operating speed, such inkjet-type image forming apparatuses (hereinafter also referred to as inkjet recording apparatuses) have become widespread for not only home use but also business use. Further, there is increased demand for forming an image on ultra-wide recording media. For business use, such an inkjet recording apparatus is provided with an ink cartridge capable of storing a large volume of ink, to reduce the frequency of cartridge replacement.
Accordingly, instead of a system in which the ink cartridge is directly mounted on the recording head, such inkjet recording apparatuses may employ a system in which the ink cartridge (also referred to as a main tank or main cartridge) is removably mounted in the image forming apparatus and connected to the recording head mounted on, e.g., a carriage via a tube to supply ink, an arrangement that is also referred to as a tube supply system.
With the tube supply system, ink consumed for image formation is supplied from the ink cartridge to the recording head via the tube. However, this system is not without its problems. For example, using a flexible thin tube may cause substantial fluid resistance for ink passing through the tube and prevent ink from being supplied on time for ink ejection, resulting in ejection failure. In particular, a large-size image forming apparatus that forms an image on a large-width recording medium necessarily uses a relatively long tube, resulting in increased fluid resistance of the tube.
Further, high-speed recording or ejection of high-viscosity ink may increase the fluid resistance of the tube, causing ink supply shortage in the recording head.
Hence, for example, in one conventional technique like that described in JP-3606282-B, ink is kept at a pressurized state in the ink cartridge and a differential-pressure regulating valve is disposed upstream of the recording head in the ink supply direction to supply ink when negative pressure in the sub tank (head tank) exceeds a threshold level.
Such a configuration may prevent the above-described ink supply (refill) shortage from occurring. However, when the pressurization method is implemented in a system in which ink is stored in an ink pack made of flexible material to secure the storage stability of ink, the ink pack may not properly deform as the volume of ink in the ink pack decreases, thus preventing the ink from being fully used.
To deal with such a failure, for example, a conventional technique like that described in JP-2006-001123-A proposes that a pump be provided at an ink output portion of the ink pack to suction ink from the ink pack. However, this technique requires a complex pump system to be provided in the ink cartridge and a driving unit for driving the pump to be provided in the image forming apparatus, increasing the cost of both the ink cartridge and the image forming apparatus.
The same situation occurs in a toner supply system of an image forming apparatus using an electrophotographic technique. For example, a technique like that described in JP-2008-134391-A proposes that air pressure to a container storing toner be used to move toner to a toner output port, thereby reducing the residual amount of toner remaining in the container. Although generally successful, there is room for improvement in this approach in terms of fully and reliably compressing the container storing toner.